Schizophrenia is a symptomatically heterogeneous disorder and it is therefore important to develop research and theory that is specifically linked to key symptoms. One such symptom is flat or blunted affect. Although recent research shows that flat affect can be rated reliably and that it is a significant prognostic indicator, little other information is known about this important symptom. To date, flat affect has been rated based on a single brief observation or review of clinical records. We will collect broader based descriptive data including multiple observations by clinicians, ward personnel and a laboratory assessment and thereby clarify the nature of flat affect. We will also examine several hypotheses about the origin of the symptom including 1) that it reflects nondominant hemisphere pathology 2) that if reflects a deficit in processing emotional cues from others and 3) that it reflects an inhibitory process.